To make the pasta dough, combine the flour and egg in a large mixing bowl (or your stand mixer, using the dough attachment) and combine. Knead the dough for ten minutes until the gluten has been activated. The dough should be smooth, and bounce back slightly to the touch. Allow the dough to rest at least 30 minutes.
Make your three-cheese filling by combining all of the ingredients in a mixing bowl. Set aside, reserving for stuffing the ravioli (or transfer to a piping bag for easier filling).
After the pasta has rested, begin to roll it out. On your pasta roller, start with the thickest stetting. Flatten out the dough (you can do this in stages, as working with smaller pieces of dough is a bit easier) and roll it through the widest setting. Then, keep rolling the dough through the machine, making the setting thinner after each pass through. The dough will become a long, thin sheet.
Fill the dough by dolloping some of the cheese filling, leaving five centimeters in between. Fold over the pasta dough, onto each dollop, then squeeze around the filling to remove any air. Using a cookie cutter or mold, cut out the desired shapes of your ravioli. Transfer to a flour-dusted sheet pan and keep covered with a damp kitchen towel as you work. Once done, the pasta can be cooked right away or wrapped tightly in plastic and transferred to the freezer.
When ready to cook (from either fresh, or frozen) drop the pasta into salted boiling water. Cook for a a minute or two if fresh, and about six minutes if cooking from frozen. When cooked, remove the pasta with a spider and transfer to a skillet with the butter. Add a splash of the cooking water and the cheese. Swirl together to form a sauce.
Transfer the sauced ravioli to a plate and top with more cheese!